System for manually ground driving trenchers and other ground engaging machinery

ABSTRACT

A manual drive system is shown for moving trenchers and other small ground engaging equipment while in operation. A preferred embodiment of the system includes a pedal providing the mechanical advantage needed for an operator to apply sufficient thrust for such operations and a cleat for engaging the ground to provide the motive force in one instance or a ratchet engaging a transport wheel in another instance.

TECHNICAL FIELD

[0001] This invention relates generally to a system for providing for manually moving trenchers and other small ground engaging equipment while in operation, as opposed to in transit. More specifically, it relates to an apparatus including a pedal providing the mechanical advantage needed for an operator to apply sufficient thrust for such operations and a cleat for engaging the ground to provide the motive force in one instance or a ratchet engaging a transport wheel in another instance. In addition, this invention comprises a separate cleat for resisting the plunge drive force that occurs when initially lowering the trenching boom assembly into the ground.

BACKGROUND ART

[0002] Trenching is required for the below ground installation of many types of utilities including electrical power, gas, telephone, water and sewer. Other types of conduits installed below ground include water lines for lawn irrigation, and drainage pipes. Many types of machines have been developed to mechanize digging trenches for such purposes. One type of machine, commonly known as a trencher, typically includes a boom assembly, which guides an excavating chain. The boom assembly is mounted to a frame or frame assembly, which typically includes a drive sprocket for the excavating chain and a power unit such as an engine to power the drive sprocket. Ground supports are attached to the frame ranging from rubber pneumatic tires to tracks. This would include transport wheels. These ground supports assist to position the frame and boom assembly relative to the ground and to propel the machine for transport and during excavation. Many of these machines have been designed to complete relatively large jobs wherein the required trenches are relatively deep, often at least 3 to 4 feet deep, and long, sometimes measuring miles in length. Such machines are typically designed such that the operator can ride on the machines. The operator's station typically includes controls for varying the ground speed during excavation (provided by controlling the drive to the ground supports) which is critical to the proper operation of the excavating chain.

[0003] Control of the position of the boom assembly is also provided in order to control the depth of excavation and to provide a transport mode wherein the boom assembly is raised above the ground surface.

[0004] Often, utilities and conduits are installed after landscaping is completed, or in spaces where the larger machines cannot maneuver or where they would cause excessive disruption of the surface. For these instances walk behind trenchers have been developed wherein the machine is much smaller, and the operator walks beside or behind the trencher. An example of such a machine can be found in U.S. Pat. No. 5,212,896. The basic components are nearly identical to those found on the larger machines, including a frame, power unit (engine), excavation boom assembly, and transport wheels. In the previously cited reference the machine is propelled during trenching by at least one of the ground engaging wheels, which is positively driven by the engine.

[0005] For many uses of such walk-behind trenchers the features provided by the ground drive are important, namely reducing the required operator effort to operate the trencher thereby increasing the capability and productivity of the trencher. Providing proper control of the ground drive system involves several components and resulting significant cost.

[0006] There is an increasing demand for less expensive, more manually operated machines for use by individuals on a limited basis. In the less demanding applications where a limited excavation depth and excavating speed is acceptable, the ground drive is not as critical, and a new ground drive system is required.

[0007] In addition to trenching machines many other types of manually operated machines require ground drive capability. Examples include roto-tillers used to cultivate gardens, concrete saws used to cut expansion joints in concrete, vibratory plows for burying cable, and snow blowers for removing snow from drives and walks. These machines would benefit from an improved ground drive.

DISCLOSURE OF THE INVENTION

[0008] The present invention involves a manual drive system, including no components powered by the engine. It is ideal for use with a walk behind trencher. The trencher includes a power unit (such as an engine or a motor) mounted on a frame supporting an excavating boom assembly and chain drive sprocket having teeth for digging and removing soil. The frame is supported on two transport wheels. The wheels rotate freely, allowing the trencher to be propelled by the operator pushing or pulling on a handle that is attached to the frame. The use of the handle is primarily intended for transporting the trencher while it is not excavating.

[0009] The present invention is a manual ground drive, separate from the handle that allows the human operator to provide the motive power to propel the trencher in the trenching direction, during excavation. This separate mechanism provides many important features including:

[0010] 1. Ergonomic efficiency: the operator propels the machine in a manner to avoid excessive use of the back.

[0011] 2. Mechanical efficiency: the ground drive force is applied to the frame at a point that the resultant effect on the excavator is to enhance performance.

[0012] 3. Mechanical efficiency: use of the drive mechanism results in a transfer of weight such that the trencher's weight is utilized to assist in developing the drive force.

[0013] 4. Mechanical efficiency: use of the drive mechanism results in a transfer of weight such that the trencher's weight is utilized to assist in keeping the boom assembly in the ground while trenching, thereby providing consistent trench depth.

[0014] In addition, a simple and reliable transport position is provided for this drive mechanism so that the drive mechanism does not interfere with the normal transport of the trencher.

[0015] The present invention further provides for a mechanism that prevents travel of the trencher in a direction opposite to that of trenching. This is critical in that the forces developed during trenching will tend to oppose trenching. If not counteracted by some mechanism, the operator will be forced to manually control the excavator to prevent this movement.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a schematic side elevation view of a trencher in a transport mode.

[0017]FIG. 2 is a schematic side elevation view of a trencher in an excavation mode.

[0018]FIG. 3 is a detailed side view of the ground drive assembly in a first, raised, position.

[0019]FIG. 4 is a detailed side view of the ground drive assembly in a second, partially lowered, position.

[0020]FIG. 5 is a detailed side view of the ground drive assembly in a third, fully lowered, position.

[0021]FIG. 6 is a detailed perspective view of the ground drive assembly.

[0022]FIG. 7 is a detailed schematic side elevation view of a trencher illustrating other features of the ground drive system.

[0023]FIG. 8 is a perspective view of a trencher.

[0024]FIG. 9 is a free-body diagram of a frame of a trencher.

[0025]FIGS. 10a-10 f are schematic side elevation views of a ground drive assembly.

[0026]FIG. 11 is a schematic side elevation view of a second embodiment using a ratchet mechanism on the transport wheels or axle.

[0027]FIG. 12, on the same sheet as FIG. 6, is a detailed schematic view of selected components of the ground drive assembly trencher.

BEST MODE FOR CARRYING OUT THE INVENTION

[0028] The preferred embodiments are shown in the drawings and described with the understanding that the present disclosure is to be considered an exemplification of the invention which is not intended to limit the invention to the embodiments disclosed.

[0029] Referring now to the drawings, wherein like reference numerals indicate like parts throughout the several views, a walk behind trencher is represented in its entirety by reference numeral 10. Trencher 10 includes a frame 12, a power unit 14, which is internal combustion engine but could be something else such as an electric motor, transport wheels 16 (which could also be tracks), an operator station 18, and an excavating boom assembly 20.

[0030] As shown in FIG. 1 the trencher 10 is in position to begin forming a trench with the transport wheels 16 and the frame 12 resting on the ground surface 8 and completely defining the orientation of the trencher 10. In this position the excavation boom assembly 20 is in the raised position for transport. The boom assembly 20 includes the boom 22, the idler roller 24 which is rotatably mounted onto the boom 22, and the excavating chain assembly 26. The excavating chain assembly 26 includes moving parts for contacting the material to be moved, which, in this case, are cutting teeth 28 mounted onto the base chain 30. The cutting teeth 28 can be any number of known types of teeth from cup cutters to rotary bits, depending on the ground conditions.

[0031] In this position the trencher can be transported by the operator by pushing down or pulling on handle 40 to rotate frame 12 counterclockwise (as seen in FIG. 1) around the axle of the ground engaging wheels 16 to raise the frame 12 off the ground so that the trencher is completely supported by the ground engaging wheels 16. Once in that position, the trencher can be propelled by the operator to transport it to the desired location to start trenching. Once in the correct location, the operator will start the power unit. The operator can then make several adjustments to the machine from the operator's station 18.

[0032] Operator's station 18 includes the handle 40, chain drive control 42, boom height control 44, ground drive assembly 45. The handle 40 is used by the operator for transport, and to help control the trencher during trenching. The chain drive control 42 is used to engage and disengage the drive from the power unit 14 to the drive sprocket 34, which is the only system driven by the power unit on the trencher. When the chain drive control 42 is pulled toward the handle 40, the drive will engage; when released, the drive will disengage.

[0033] The boom height control 44 is used to control the orientation of the boom assembly 20 relative to the frame 12. FIGS. 7 and 8 illustrate the boom height control 44 including an actuating arm 54, latching bar 56, latch plate 58, spring 60 and link 62. The spring 60 pulls the latching bar 56 into one of four grooves 59, which define four positions. In order to change the orientation the operator pulls on the upper end of latching bar 56, which will lift the opposite end of the latching bar 56 out of the groove 59 and allow the actuating arm 54 to rotate relative to the frame 12. This rotation will move link 62 as can be seen in FIG. 7, which has one end pivotally attached to the actuating arm 54 with the other end (not shown) pivotally attached to the excavating boom 22. Once the boom height control 44 is positioned such that latch bar 56 is in the desired groove 59 the latch bar 56 is released and the orientation of boom 22 is fixed.

[0034] The operator will then pull on the chain drive control 42 to engage drive to the excavating chain, typically while pushing down on the handle 40 to raise the excavating boom assembly 20 off the ground. To start excavating the trench, the operator will allow the trencher to rotate clockwise (as oriented in FIG. 7) around the axle of the ground engage wheels 16 with the excavating chain powered. The boom assembly 20 will thus be lowered, plunging into the ground, until the frame 12 is resting on the ground as shown in FIG. 2. This first step of excavation is known as plunge cutting.

[0035] This initial plunge cut requires that the trencher be held stationary while the excavating chain is contacting the ground generating a plunge drive force, attempting to propel the trencher from left to right, as shown in FIG. 2. In a trencher with ground drive this plunge drive force is offset by the ground drive system connected to the transport wheels. With the trencher of the present invention there is no drive mechanism associated with the transport wheels 16. Thus, some other means of counteracting the plunge drive force is required. If no other mechanism were provided, the operator would be required to hold the trencher to counteract this plunge drive force.

[0036] In the embodiment illustrated, specifically in FIGS. 2 and 7, a ground engaging cleat member 52 is designed to counteract the plunge drive force. The ground engaging cleat 52 is pivotally attached to the frame 12. It is positioned with a chain link 64, which is connected to the boom height control link 62 such that when the boom is raised to the transport position ground engaging cleat member 52 is raised, as shown in FIG. 7. When the boom is lowered to an excavating position the ground engaging cleat 52 is lowered as shown in FIG. 2. In the lowered position the ground engaging cleat 52 will prevent the trencher from moving in a direction opposite the direction of trenching (toward the boom), thus counteracting the plunge drive force and eliminating the need for the operator to hold the trencher against this plunge drive force.

[0037] Once the excavating boom is properly lowered into the ground, as shown in FIG. 2, the trencher is propelled toward the operator 's station 18 in order to extend the length of the trench. Without any other mechanism, and as found on currently available manually operated models, the operator pulls on the handle with force 66 to move the trencher a relatively short distance to the left. This action of pulling on the handle effectively applies a counterclockwise moment (as observed in FIG. 2) on the trencher, which tends to rotate the trencher counterclockwise and is normally accompanied by a significant amount of lifting of the boom assembly. The trencher will then be held in position while effectively plunge cutting again to get back to the desired trench depth. In this manner the trench is extended, effectively performing many small plunge cuts. The present invention however, provides an alternate method of propelling the trencher during the trenching process.

[0038] The ground drive assembly 45 shown in FIG. 3 is provided to aid in propelling the machine (FIG. 3 depicts any number of manually driven machines as indicated by the generic component 100, taking the place of the trenching mechanism, the roto-tiller blades, concrete saws, vibratory plows, snow blowers, etc.). It includes pedal 46 and ground engaging member 50. In use the mechanism starts in the non-ground engaging position illustrated in FIG. 3 with the ground drive lever (shown as a pedal, but could be any lever, including the handle 40) 46 in the raised position due to the force of spring 72. The ground drive lever 46 is pivotally attached to the frame at pivot point 74. Ground engaging member 50 is pivotally attached to the ground drive lever at pivot point 76. The ground engaging member 50 is constructed from a single plate, with two ears 94 bent up as can be seen in FIG. 6, and a rear surface 98. The ears 94 contain holes defining the ground engaging member pivot point 76. Ground drive lever 46 also includes cooperating holes to define the ground engaging member pivot point 76. The ground engaging member 50 overlaps the ground drive lever 46 such that the range of motion is restricted. The ground engaging member 50 cannot rotate clockwise (as oriented in FIG. 3) around its pivot point 76 any further than as shown in FIG. 3. As shown in FIG. 6, this point is defined when the edge of rear surface 98 contacts the lever 46. Spring 78 pulls the ground engaging member 50 into this position.

[0039] To propel the trencher the operator 6 depresses the ground engaging member 46 down with foot force 68 as shown in FIG. 4. When the ground engaging member 50 contacts the ground, the trencher begins to be propelled. Looking at the free-body diagrams of the frame and of the drive mechanism as illustrated in FIGS. 9 and 10 one can see the advantages of this drive arrangement.

[0040]FIG. 9 illustrates a free-body diagram of the frame 12 and handle 40. The potential forces applied to the frame can be summarized by the six forces: handle force 66, the operator's force on the handle 40, ground drive force 80, the force that the ground drive mechanism can generate, wheel force 82, the force generated by the wheels to support the load, excavate force 84, the force the excavating chain develops while excavating, ground force 85, the force provided by the ground surface 8 (FIG. 1), and the machine's weight 83. In propelling the trencher with just the handle force 66, it is evident, by looking at the sum of the moments about the transport wheels' axle 77, that the handle force 66 generally must be in a direction opposite that required (and shown 66) to propel the trencher, from right to left, in order to counteract the excavate force 84. Excavate force 84, as illustrated, will tend to make the frame rotate counterclockwise around the wheel axle 77. Thus, the operator typically must push on handle 40, in a direction opposite that shown, for force 66 to force the frame to rotate clockwise and force the excavating assembly 20 to stay engaged with the ground in order to maximize the excavating efficiency. Thus, it is unavoidable that when the trencher is propelled by pulling on handle 40 with force 66, the frame is forced to rotate counterclockwise about the wheel axle 77, effectively acting in conjunction with the excavate force 84. This transfers load to the transport wheels and lifts the boom 22 out of the ground, effectively reducing the excavator's capacity and productivity.

[0041] With the ground drive of the present invention there is no force applied to the handle. Handle force 66 is zero, and the ground drive assembly 45 is utilized to propel the trencher; with a completely different effect on the excavate force 84.

[0042] The effective angle of the ground drive force 80, α, changes with the position of the ground drive mechanism as illustrated in FIG. 10. In the position shown in FIG. 10a the ground engaging member 50 is just beginning to contact the ground 8. In this position the member 50 cannot rotate counterclockwise on its pivot 76 due to the construction described earlier. Assuming that the contact between the ground 8 and the ground engaging member 50 is sound, the assembly, pedal 46 and ground engaging member 50, will be forced to pivot around that point of contact 86. The resulting ground drive force 80 will thus be perpendicular to a line drawn between the contact point 86 and the pivot point 74, resulting in an effective angle α as illustrated. As the pedal 46 is depressed further, effective angle α will decrease as the line drawn between contact point 86 and pivot point 74 becomes closer to vertical as shown in FIGS. 10b and 10 c. In FIG. 10d the line drawn between the contact point 86 and pivot point 74 is vertical, and the ground drive assembly 45 is poised to go over-center. Over-center means that the cleat 50 will begin to pivot counterclockwise relative to the pedal 46, as shown in FIGS. 10e and 10 f.

[0043] As the operator 6 begins to depress the lever 46 the pivot point 74 is raised, as is evident by comparing FIG. 10b with FIG. 10a. This will result in a transfer of forces. As pivot point 74 is raised, force 82 is partially transferred to pivot point 74. The balance of force 82 is transferred to add to force 85. The wheels no longer provide support as the ground drive 45 is now supporting the machine. This results in an increase in the ability of machine weight force 83 to counteract excavate force 84. Looking again at FIG. 9, and summing moments around the transport wheel axle's axis 77, as ground drive force 80 is increased, force component 80 y (shown in FIG. 10) works in conjunction with machine weight 83 to counteract excavate force 84. In addition, force component 80 x (shown in FIG. 10) counteracts excavate force 84. Thus, as the operator propels the machine with the ground drive assembly 45, the excavator boom assembly will simultaneously be forced into contact with the ground actually improving the excavator's capacity and productivity.

[0044] The complete drive cycle defined by one stroke of the ground drive mechanism 45, illustrated in FIG. 10, results in the following conditions:

[0045] 1. At FIG. 10a the excavator frame 12 is initially urged vertically by vertical force 80 _(y) while simultaneously urged horizontally by a horizontal force 80 _(x) resulting in an initial transfer of load from the transport wheels to the contact point 86 and excavator pivot 88. The increased load at excavator pivot 88 will enhance the excavator performance.

[0046] 2. At FIGS. 10b and 10 c the excavator frame 12 has been raised, with the transport wheels potentially not carrying any weight. The effective angle a changes and the resulting ground drive force 80 is more effectively horizontal, as can be seen by comparing horizontal force 80 _(x) to vertical force 80 _(y).

[0047] 3. At FIG. 10d the ground drive assembly 45 is at the point of going over-center, at which point the effective angle a is zero and the resulting force will be exclusively horizontal. This is due to the free rotation allowed by the ground drive pivot point 76.

[0048] 4. At FIGS. 10e and 10 f the ground engaging member 50 continues to pivot about its pivot point 76, the pivot point 74 lowers, with gravity, and the trencher continues to be propelled from right to left. In this stage of the cycle gravity is actually assisting to propel the trencher.

[0049] At the end of this cycle the operator will release lever 46, the spring 72 will retract lever 46 to its original position as in FIG. 10a, spring 78 returns ground engaging member 50 to its original position as in FIG. 10a, and the drive cycle is ready to start again. This drive cycle can be completed as necessary to extend the trench to the desired length.

[0050] When the trench is complete the operator can transport the trencher. As explained earlier this is accomplished by pulling on handle 40 to rotate the trencher counterclockwise (as oriented in FIG. 1) around the wheels 16 in order to raise the boom assembly 20 out of the trench. However, as shown in FIG. 2, the amount that the trencher can be rotated counterclockwise is limited by ground engaging member 50, as it will quickly contact the ground. In order to increase the distance the trencher can be rotated, a latch 48 for the ground engaging member 50, is provided. As illustrated in FIGS. 6 and 12 latch 48 is mounted on pivot 96 and includes a flat 92 and tab 90. It freely rotates on pivot 96 such that it hangs, by gravity, in the position illustrated in FIG. 6. When the operator wishes to latch the ground engaging member 50 up the ground engaging member is pushed to rotate clockwise until the edge of rear surface 98 moves far enough to allow the latch 48 to rotate, by gravity, counterclockwise into the position shown in FIG. 12. In this position, ground engaging member 50 is latched up and out of the way for transport, etc.

[0051] The above description is one embodiment of the invention. A second potential embodiment is one wherein the handle 40 could be constructed with a pivot such that the ground drive assembly 45 could be actuated by the handle. Thus, the handle becomes the lever described above.

[0052] An additional embodiment is illustrated in FIG. 11 and entails utilizing the lever 46 (or handle 40) to engage a ratchet wheel attached to the transport wheels 16, the axle on which at least one transport wheel is rigidly attached, or additional ground driving wheels. Here, the machine is manually driven using wheels which engage the surface of the ground sufficiently to apply a horizontal thrust. Generic component 100 indicates that FIG. 11 represents any number of manually transported machines (some of which are referred to above), including, but not limited to, a trencher.

[0053] To operate the FIG. 11 embodiment, the operator 6 presses down on pedal 46. Link 90 engages tooth 91 and causes wheel 16 to turn in the direction of trenching. Spring 92 keeps link 90 engaged against teeth 91. When stroke of pedal 46 is completed, operator 6 lifts foot and spring 72 returns pedal 46 to original position, ready for next stroke. During return, trenching stake 52 engages the ground and holds the machine in place, resisting movement in a direction opposite trenching, until the beginning of the next stroke.

[0054] This invention is not intended to be limited to trenching equipment. Additional equipment on which this invention has application include roto-tillers, concrete saws, vibratory plows, and snow blowers.

[0055] Obviously many other modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. 

We claim:
 1. Apparatus comprising: a frame; transport wheels operatively attached to said frame for moving said frame from place to place; a tool operatively attached to said frame, said tool having moving parts for contacting material to be moved; a power unit operatively attached to said frame and operatively attached to said tool for moving said parts whereby said parts can move material disposed adjacent to said frame; and a ground engaging member having a raised non-ground engaging position and a plurality of ground engaging positions for causing said frame to move in a predetermined direction as said ground engaging member moves from said non-ground engaging position to progressive ones of said plurality of ground engaging positions.
 2. The apparatus of claim 1 including a ground engaging cleat member operatively attached to said frame and movable between a raised non-ground engaging position and a lowered ground engaging position for tending to hold said frame from moving in a direction opposite to said predetermined direction.
 3. The apparatus of claim 1 including a lever operatively pivotally attached to said frame for causing said ground engaging member to move between said raised non-ground engaging position and said plurality of ground engaging positions.
 4. The apparatus of claim 3 wherein said ground engaging member is operatively pivotally attached to said lever.
 5. The apparatus of claim 4 wherein said lever is a pedal for being pushed downwardly by a foot of an operator of said apparatus.
 6. The apparatus of claim 1 including a handle operatively attached to said frame for grasping by said operator.
 7. The apparatus of claim 6 wherein said tool is a trencher and said predetermined direction is a direction of trenching and said frame is also moveable in a direction opposite to the direction of trenching.
 8. The apparatus of claim 7 wherein when said ground engaging member moves from said non-ground engaging position to said plurality of ground engaging positions said ground engaging member pivots in said direction opposite to a direction of trenching, thereby causing said frame and said trencher to move in said direction of trenching.
 9. The apparatus of claim 1 wherein said tool is a roto-tiller.
 10. The apparatus of claim 1 wherein said tool is a concrete saw.
 11. The apparatus of claim 1 including means for locking said ground engaging member in a raised transport position thereof.
 12. The apparatus of claim 1 including a spring operatively attached to said frame for biasing said lever to an upward position.
 13. The apparatus of claim 1 including a spring operatively attached to said frame for biasing said ground engaging member to said raised transport position thereof.
 14. The apparatus of claim 13 wherein said spring is directly pivotally attached to said lever and is thereby indirectly attached to said frame.
 15. Apparatus comprising: a frame; transport wheels operatively attached to said frame for moving said frame from place to place; a tool having moving parts, said tool being operatively attached to said frame; a power unit operatively attached to said frame and operatively attached to said tool for moving said parts whereby said parts can move material disposed adjacent to said frame; a lever operatively pivotally attached to said frame; a ratchet wheel operatively attached to said transport wheels, said ratchet wheel having teeth disposed about the outer periphery thereof; and a link member operatively pivotally attached to said lever and biased toward said ratchet wheel for causing said link member to contact said teeth and thereby turn the transport wheels whereby the frame will be moved in a predetermined direction as said link member is moved downwardly by movement of said lever.
 16. The apparatus of claim 15 including a ground engaging cleat member operatively attached to said frame and movable between a raised non-ground engaging position and a lowered ground engaging position for tending to hold the frame from moving said frame in a direction opposite to said predetermined direction.
 17. The apparatus of claim 15 wherein said lever is a pedal for being pushed downwardly by a foot of an operator of said apparatus.
 18. The apparatus of claim 15 including a handle operatively attached to said frame for grasping by said operator.
 19. The apparatus of claim 15 wherein said tool is a trencher and said predetermined direction is a direction of trenching.
 20. The apparatus of claim 15 wherein said tool is a roto-tiller.
 21. The apparatus of claim 15 wherein said tool is a concrete saw.
 22. The apparatus of claim 15 wherein said tool is a vibratory plow.
 23. The apparatus of claim 15 wherein said tool is a snow blower.
 24. The apparatus of claim 1 wherein said tool is a vibratory plow.
 25. The apparatus of claim 1 wherein said tool is a snow blower. 